In the field of digital image processing, particularly video image processing, a so-called dithering method is applied, for example to create the illusion of color depth in images with a limited color palette. For example, one common application of dithering is to more accurately display graphics containing a greater range of colors than the hardware is capable of showing. The dithering takes advantage of the human eyes' tendency to mix two colors in close proximity to one another. For example, by alternating each pixel's color value in an LED display, roughly between two approximate colors in the LCD panel's color space, the display panel which natively supports a certain color depth can represent a much higher color depth.
The same principles may also be used for a more accurate luminance in an LCD display in which each pixel only “knows” an ON or OFF state and no intermediate values. By using dithering, the user gets the impression of intermediate luminance values between 0 (off) and 1 (on).
Dithering is frequently used in TV sets, particularly also in TV sets having high frame rate processing units which provide viewer image frames with a high rate of, for example, 200/240 Hz. In such systems, the dithering is applied to the video image frames with a low frame rate, for example 50/60 Hz.
One of the problems of such systems is that the dither will be visible at the high frame rate processing unit.